The present invention describes processes for the chemical synthesis of unsaturated C-18 ketones which can be readily converted to phytol (3,7,11,15-tetramethyl-2-hexadecen-1-ol) and isophytol (3,7,11,15-tetramethyl-1-hexadecen-3-ol). Both phytol and isophytol can be used in the manufacture of alpha-tocopherol (the most active vitamin E factor known to occur in nature), and in the synthesis of vitamin K . Novel chemical intermediates used in the preparation of isophytol and phytol are also disclosed herein, as well as procedures for synthesizing these intermediates.
Synthesis of phytol generally requires lengthy sequences of reactions as exemplified in the following references: B. C. L. Weedon, et al., J. Chem. Soc. (C), 2144 (1966); K. Sato, et al., J. Org. Chem., 32, 177 (1967); and T. Fujisawa, et al., Tetrahedron Lett., 22, 4823-4826 (1981). F. G. Fischer and K. Lowenberg, Ann., 475, 183-204 (1929), have reported a synthesis of phytol (and isophytol) utilizing the C-18 ketone (1) shown below as the key intermediate: ##STR1##
Treatment of either phytol or isophytol with the commercially available trimethylhydroquinone and an acid catalyst affords alpha-tocopherol, as outlined below [See: pages 392-3 in "Chemistry of Vitamin E" by O. Isler, et al.; a chapter in Vitamins and Hormones: Advances in Research and Applications, Volume 20, edited by R. S. Harris, et al. (Academic Press, 1962). ##STR2##
Other processes for synthesizing vitamins E and K.sub.1 are illustrated in Chem. Abstracts, 67, 100,297z (1967); in a chapter in Vitamins and Hormones: Advances in Research and Applications, Volume 20, edited by R. S. Harris, et al. (Academic Press, 1962, pages 389-405); in N. Cohen, et al., J. Am. Chem. Soc., 101, 6710 (1979); and, in K. Chan, et al., J. Org. Chem., 43, 3435 (1978).